FLINT, MI - State officials warned of potential health problems if Flint were to switch to the Flint River as its drinking water source, but the move went ahead with the state's blessing despite the concerns, according to emails released by the Michigan's governor's office Friday morning.

Stephen Busch, with the Michigan Department of Environmental Quality's drinking water division, told other DEQ officials in a March 26, 2013, email that the use of the river could lead to multiple problems, including increased disinfectant by-products and microbials in the water, which could put the public's health at risk.

According to Busch's email, continuous use of the river could pose an increased microbial risk and risk of potentially cancer-causing disinfection by-products.

Both the disinfectant by-products and microbials -- viruses and bacteria linked to disease -- were discovered in the city's water supply in the months after the city was switched to the river in April 2014.

Busch, who was later suspended after elevated lead levels were found in Flint children following the switch, raised the warnings as state officials reviewed whether the city should accept a deal to stay with its Detroit drinking water source or join the new Karegnondi Water Authority.

The city -- which was under control of a state emergency manager at the time -- switched to KWA and went to the Flint River as a stopgap drinking water source until the new pipeline was finished.

Busch's concerns were sent to then-DEQ Director Dan Wyant and eventually forwarded to the state Department of Treasury, which signed off on the switch to the KWA and the Flint River.

City officials began issuing boil water advisories in August 2014, months after the switch, as fecal coliform bacteria was found in the city's water supply. Additional boil water advisories were issued in September 2014 after multiple positive tests for total coliform bacteria, an indication of a possible pathway for pathogens and fecal contamination to enter a drinking water system.

The switch to the river also was investigated as a potential source of a Legionnaires' disease outbreak that left nine dead and nearly 80 others ill. The river has not been conclusively linked to the outbreak.

The city sent out notices in January 2015 telling residents it was violating the Safe Drinking Water Act after too many disinfection by-products were discovered in the city's water. The notices claimed Flint water was safe to drink but warned that those with "a severely compromised immune system, (who) have an infant or are elderly" that they "may be at increased risk and should seek advice about drinking water from your health care provider."

The city issued the notices due to increased levels of trihalomethanes -- or TTHM -- a group of four chemicals that are formed as a byproduct of disinfecting water. TTHM is a colorless, odorless byproduct of chlorinating water with high levels of total organic carbon.

People who drink water with TTHM in excess of the maximum contaminant level over many years may experience problems with their livers, kidneys or central nervous systems and have an increased risk of getting cancer.

The city restored its compliance with the Safe Drinking Water Act in September 2015.

Wyant, roughly 26 hours after Busch issued the email, forwarded the concerns, along with the DEQ's support of the KWA, to state Treasurer Andy Dillon, who was required by state law to sign off on the change since the city was being run by an emergency manager.

"All indications are that we are supportive of KWA and its cost benefits compared to DWSD options," Wyant wrote. "If that is not the answer you want tomorrow - then we should discuss."

DEQ spokeswoman Mel Brown declined to comment on how Busch's concerns were handled due to changes in leadership in the agency.

Wyant resigned in December 2015. The state announced in January that Busch was suspended pending an investigation into how the agency handled the city's drinking water crisis.

Treasury spokesman Terry Stanton said the issues raised by Busch were discussed on a call between DEQ staff and Dillon. He added that the emails showed the DEQ was supportive of the switch to the KWA.